Physiology Feeding and Satiety

Question 1

What is energy homeostasis?

Answer 1

Physiological process whereby energy intake is matched to energy expenditure over time

Question 2

How do you calculate BMI?

Answer 2

Weight/Height(m) (squared)

Question 3

What BMI is thin or normal?

Answer 3

Up to 25

Question 4

What is classed as overweight?

Answer 4

25-29.9

Question 5

What is classed as obese?

Answer 5

30-39.9

Question 6

What is classed as morbidly obese?

Answer 6

BMI of more than 40

Question 7

What are the major factors influencing obesity?

Answer 7

Genetics - fatness runs in families

Environment - westernisation of diet

Question 8

What is energy balance disturbance?

Answer 8

Difference between energy intake and expenditure

Question 9

What can obesity lead to, in terms of contribution to disease and premature mortality?

Answer 9

Type 2 diabetes 
High BP 
Heart attack 
Cancers (colon) 
Osteoarthritis

Question 10

Why do we need fat?

Answer 10

Energy storage
Prevention of starvation
Energy buffer during prolonged illness

Question 11

Why can it be difficult to lose weight in terms of the brain?

Answer 11

Increased body fat alters the brain function, long term obesity induces brain ‘re-programming’.

Your brain views the extra weight/fat as normal and dieting as a threat to body survival (i.e. it defends the new weight)

Question 12

How does the CNS influence energy balance and body weight?

Answer 12

Behaviour - feeds and physical activity
ANS activity - regulates energy expenditure
Neuroendocrine system - secretion of hormones

Question 13

What might damage of the ventromedial hypothalamus cause?

Answer 13

Obesity

Question 14

What might damage of the lateral hypothalamus cause?

Answer 14

Leanness

Question 15

What is satiation?

Answer 15

The sensation of feeling full during a meal

Question 16

What is satiety?

Answer 16

The period of time between meals

Question 17

What is adiposity?

Answer 17

The state of being obese

Question 18

Do satiation signals increase during meals to limit meal size?

Answer 18

YES

Question 19

Describe the 5 secretions that are secreted - satiation signals?

Answer 19

Cholecystokinin (CCK)
Peptide YY (PYY3-36)
Glucagon-like peptide 1 (GLP-1)
Oxyntomodulin (OXM)
Obestatin

Question 20

Describe what CCK - cholecystokinin does?

Answer 20

It is secreted from the enteroendocrine cells in the duodenum and jejunum.
It is release in proportion to lipids and proteins in meals.
It signals via sensory nerves to hindbrain and stimulates hindbrain directly (Nucleus of solitary tract (NTS))

Question 21

Describe what PYY3-36 - peptide YY does?

Answer 21

It is secreted from endocrine mucosal L-cells of the GI tract
Levels increase rapidly post meal.
It inhibits gastric motility, slows emptying and reduces food intake (hypo)

Question 22

What does GLP-1 - glucagon like peptide 1 do?

Answer 22

It is a product of pro-glucagon gene.
It is also released from L cells in response to food ingestion.
It inhibits gastric emptying and reduces food intake (Hypo, NTS)

Question 23

Describe what OXM - oxyntomodulin does?

Answer 23

It is also a produce of pro-glucagon gene and it is released from oxyntic cells of the small intestine after a meal.
It surpasses the appetite

Question 24

What is obestatin and what does it do?

Answer 24

It is a peptide produces from the gene that encodes ghrelin and it is released from cells lining the stomach and small intestine.

Question 25

What is ghrelin?

Answer 25

It is a hunger signal

Question 26

What is ghrelin secreted by?

Answer 26

Oxyntic cells in the stomach

Question 27

What happens to the levels of ghrelin before meals and after meals?

Answer 27

Increase before meals

Decrease after meals

Question 28

What 2 hormones report fat status to the brain?

adiposity signals

Answer 28

Leptin

Insulin

Question 29

Describe where leptin is made and released?

Answer 29

From the fat cells

Question 30

Describe where insulin is made and released from?

Answer 30

The pancreatic cells

Question 31

How do the levels of leptin and insulin in the blood vary as more fat is stored?

Answer 31

Levels in the blood increase as more fat is stored

Question 32

What does reduced leptin mimic and thus cause?

Answer 32

Mimics starvation causing unrestrained appetite

Question 33

What are some of the biological roles of leptin?

Answer 33

Food intake/energy expenditure/fat deposition
Peripheral glucose homeostasis/insulin sensitivity
Maintenance of immune system
Maintenance of reproductive system
Angiogenesis
Tumourigenesis
Bone formation

Question 34

What is the current treatment for obesity?

Answer 34

Orlistat

Question 35

What does orlistat do?

Answer 35

Inhibits pancreatic lipase, decreasing triglyceride abdorption
Reduced efficiency of fat absorption in small intestine

Question 36

What are some side effects of orlistat?

Answer 36

Side-effects include cramping and severe diarrhoea

Question 37

Describe gastric by pass surgery

Answer 37

Produces substantial weight loss in one year thats sustainable
Surgery induces high level of completely resolution of type 2 diabetes

Question 38

What is Adaptive Thermogenesis?

Answer 38

This can be defined as the regulated production of heat in response to environmental changes in temperature and diet, resulting in metabolic inefficiency. For example, shivering when we are cold uses energy and this is an example of adaptive thermogenesis